Shell Programming and Scripting

Originally Posted by Kibou

Another thing.

If testing something like this (contents of test.sh)
(This code is not inside a loop.)

Code:

var3=1
case $var3 in
  1) var1=1
     break ;;
  2) var1=1
     var2=2
     break ;;
  *) echo "Error" ;;
esac

The thing is that when executing this code with ksh (RHEL 6.5) there's no error message from the shell.

But when executing with bash there's an error message when case has to evaluate a condition with break. When executed with ksh or sh, there's no error message.

Code:

[root@xxxx]# bash test.sh
test.sh: line 5: break: only meaningful in a `for', `while', or `until' loop
[root@xxxx]# ksh test.sh
[root@xxxx]# sh test.sh

As far as I know, break it has sense only when there's a loop. But since there's no error message for ksh and sh it looks like the behaviour for case is different from bash.

case syntax without break works fine in ksh and sh, with no error messages. Same with bash, as expected.

Any thoughts about this behaviour?

This is probably the same behaviour in ksh-AIX but I couldn't access a machine to test it right now.

The break utility shall exit from the smallest enclosing for, while, or until loop, if any; or from
the nth enclosing loop if n is specified.

Originally Posted by bakunin

So, i take it, this is because "[" is a shell builtin. (Which it is indeed - i had the wrong impression that "[" is external and "[[" is the builtin, but i learned otherwise through experiment. In fact "[" is a builtin and "[[" is a reserved word, according to my system shell on AIX, a ksh88.)

This seems to be in line with the following analogous lines, where "x" and "$x" can be used interchangeably:

Code:

x=5 ; let x=x+1
x=5 ; let "x = x + 1"
x=5 ; (( x += 1 ))
x=5 ; echo $(( x ))

I wonder how the parsing process of the ksh works so that this is only the case for integers (or - for the shell obviously being the same - strings which evaluate to integers). One would think that variables either get expanded or not, but it would not depend on their content if they are.

bakunin